1. Field of the Invention
This invention relates to containers having a closeable flap, such as envelopes, and more particularly to such devices having provisions for permanently sealing the flap shut with a wettable dry glue and temporarily sealing the flap shut with a pressure sensitive adhesive.
2. Description of the Prior Art
(The term "prior art" as used herein, or in any statement by or on behalf of applicant, means only that any document or thing referred to as prior art bears directly or inferentially, a date which is earlier than the effective filing date hereof).
Envelopes, and similar containers having an opening bordered by a flap, have been known for many years. While occasionally mechanical devices, such as clasps, strings, and snap fasteners, are used for holding the flaps shut, it is much more popular to provide a layer of wettable dry adhesive on the inside of the flap which, when wetted, can be folded against the body of the container to secure the flap in closed position.
The wettable dry adhesive seal is permanent in nature and requires that the integrity of the envelope be destroyed in order to gain access to its contents. Since the advent of pressure sensitive adhesive, envelopes have been made with flaps bearing areas of pressure sensitive adhesive by which the envelope flap may be releasably secured in place a number of times so that the envelope may be used over and over again. Such envelopes are not suitable for mailing because of the ease with which they can be opened and the contents of the envelope removed.
Examples of envelopes having pressure sensitive adhesive on their flaps may be found in U.S. Pat. No. 2,367,440 to G. Schieman; U.S. Pat. No. 2,601,946 to V. Heywood; and U.S. Pat. No. 4,192,448 to E. Porth. Examples of tabs bearing pressure sensitive adhesive for temporary sealing of envelopes are found in U.S. Pat. No. 934,279 to R. Voysey; U.S. Pat. No. 2,400,406 to A. Godoy; U.S. Pat. No. 3,265,289 to W. Hiersteiner; and U.S. Pat. No. 3,712,171 to E. Levine.
Attempts have been made to make an envelope which can either be permanently or temporarily sealed. West German Patent No. 26 47 357 shows and describes an envelope having parallel adhesive bands, the first band being for permanent sealing and the second band being a pressure sensitive adhesive allowing repeated sealing of the envelope. French Patent No. 75 05716 shows and describes an envelope having a section of the flap covered with a pressure sensitive adhesive and two sections on the body of an envelope, one of the sections being coated with an adhesive which adheres permanently to the adhesive on the envelope flap, and the second section having an easy-release coating for temporary sealing.
In addition to the patents discussed above, it is believed that U.S. Pat. No. 2,224,604 to C. Miehlke contains information which is or might be considered to be material to the examination of this application. The cited patents are believed to be relevant to the present invention because they were reduced by a prior art search made by an independent searcher.
A copy of each of the above-listed and above-discussed patents is supplied to the Patent and Trademark office herewith.
No representation or admission is made that any of the enclosed documents is part of the prior art, in any acceptation of that term, or that no more pertinent information exists.